1. Field of the Invention
The present invention is generally related to the field of caching, and, more specifically, to systems and methods for updating a cache.
2. Discussion of the Background
A cache is a data storage medium that is used by software (e.g., a computer program) to store recently accessed data that was retrieved from a relatively slower storage medium. The purpose of a cache is to speed up subsequent access to the data. A cache is most often applied to processor-memory access but is also used for storing locally a copy of data accessible over a network.
For example, in a client-server environment where data is centrally stored and managed on a central server (i.e., main storage unit) and software requiring that data runs on a client, a cache for storing the data is created on the client so that the software need not always request the data from the server: the software can request the data from the cache. By having the ability to retrieve the data from the cache as opposed to retrieving it from the server, the software is able to more quickly access the data.
However, in order for the software to function properly, the cache must be periodically updated to ensure that the cache stores the most up to date data. That is, for example, it is desirable to avoid the situation where the cache stores a much earlier version of a file than is stored in the main storage unit.
In the client server environment where there are many clients and each client has its own cache, a network overload problem can occur if several or more of the caches are updated at about the same time. This situation typically occurs when the software that updates the cache is programmed to do so shortly after the software is launched.